Surgical instruments, in particular surgical sliding shaft instruments, have to be cleaned after each use. In doing so, it is also necessary to clean surfaces that are arranged between different components of the instruments. For this purpose, the instruments are designed such that they can be dismantled into several parts. The instrument has, on a guide element, a rail that is oriented along a slide element and that has a proximal part and a distal part. The distal part of the rail has an undercut profile. The proximal part of the rail has a mounting opening. Moreover, the sliding shaft instrument has a slide element, which comprises a profile web with a profile matching the rail profile. The profile web engages in the rail. The slide element, which is arranged slidably on a guide element, can be released from the guide element as a result of the dismantling, such that the slide surfaces can be cleaned. The slide element with the profile web is pushed to the proximal end of the rail, such that the profile web is arranged in the mounting opening, from which it can be released from the rail. To prevent dismantling during a surgical intervention, a locking mechanism is provided.
It is known from DE 20 2008 001 675 U1 to initiate the dismantling of the sliding shaft instrument by moving two grip parts wide open. For this purpose, a slide element, which is mounted slidably on a guide element, has a guide groove at its proximal end, said guide groove being composed of two parts. The guide groove is oriented in the direction of movement of the slide element. The distal part of the guide groove is narrower than the proximal part of the guide groove. Moreover, the guide element has, at its proximal end, a locking slide, which engages in the proximal part of the guide groove. The transition between the proximal part and the distal part of the guide groove is rounded by radii. By means of the transition, the slide element is stopped by the locking slide during the opening of the grips of the sliding shaft instrument, such that a dismantling of the sliding shaft instrument is prevented.
DE 197 48 369 C2 relates to a dismantlable sliding shaft instrument which has, as locking mechanism, a rotation safety element. The rotation safety element is designed as a rotatably mounted disk. The disk is arranged at the proximal end of the guide element such that it blocks the path of the slide element. The disk has a recess which, for unlocking purposes, is rotated to the slide element. The blocking of the slide element is thereby canceled. Moreover, the locking element can also be arranged on the movable grip part of the sliding shaft instrument. In this case, the locking mechanism blocks the opening of the second grip part by form-fit engagement with the underside of the guide element.
The abovementioned locking mechanisms have in common the disadvantage that they are unable to guarantee secure locking. Thus, when the locking mechanism is designed as a slide, a bending of the locking slide can be caused by the guide groove rounded with radii. Moreover, the locking slide may be bent by forcible opening of the grip elements of the sliding shaft instrument, such that an inadvertent dismantling of the sliding shaft instrument may occur in both cases. In the embodiment with the rotation safety element, accidental opening may be caused by the free rotatability of the safety means. Therefore, in this embodiment too, an inadvertent dismantling may occur during a surgical intervention.
It is also known to equip the rotation safety element with a locking element. The locking element is arranged on a pin stub, which is coupled to a bushing arranged on the grip part. The pin stub is mounted movably in its axial direction. The bushing also has a recess, into which the locking element is placed when securing the slide element. A disadvantage of this device is that the rotation safety element can cause a locking of the slide element in different positions. However, secure locking is ensured only in a position in which the locking element is arranged in the recess of the bushing. Consequently, incorrect positioning of the rotation safety element can lead to accidental dismantling of the sliding shaft instrument.